GitLab

Output structure:
<ProfileDir>
    WebApps
        Sync Data
            LevelDB
        Temp
            <temp_name>
                Icons
                    <size1>.png
                    <sizeN>.png
        <AppId1>
            Icons
                <size1>.png
                <sizeN>.png
        <AppIdN>
            Icons
                <size1>.png
                <sizeN>.png

When all .png files written, we `mv` Temp/<temp_name> to WebApps/<AppId1> in one final
file system "commit".

TBR=dcheng@chromium.org

Bug: 901226
Change-Id: I2e8840aa3df230d9f78f287d5a637780ef34268b
Reviewed-on: https://chromium-review.googlesource.com/c/1349148Reviewed-by: Alexey Baskakov <loyso@chromium.org>
Reviewed-by: Alan Cutter <alancutter@chromium.org>
Commit-Queue: Alexey Baskakov <loyso@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611589}